A sign indicating "Traffic signals ahead" serves what purpose?

A sign indicating "Traffic signals ahead" is designed to prepare drivers for the presence of traffic signals that they will encounter shortly. This type of sign serves a critical purpose in traffic management by alerting drivers to adjust their speed and be ready to stop or proceed accordingly. Anticipating potential changes in traffic flow helps ensure safer driving conditions, allowing drivers to react appropriately to the signals once they come into view.

The other options relate to different aspects of road management. Informing about speed limits focuses on the maximum speed a vehicle can legally travel in a certain area, while directing traffic off the main road pertains to rerouting vehicles, commonly done for detours. Announcing a construction zone is meant to alert drivers to reduced speed and heightened caution due to work on or near the roadway. Each of these serves a specific function but does not relate to the immediate alerting of upcoming traffic signals, making "Traffic signals ahead" distinctly focused on preparing drivers for forthcoming signal control.